Xenicanes are a family of diterpene natural products. As shown in FIG. 1, representative members of the xenicane family have been reported to possess a variety of beneficial biological properties (also see for Example J. Nat. Prod. 2007, 70, 1551).
Compounds of the xenicane family vary in oxidation state of the cores and side chains. Some derivatives possess additional rings. The florlides contain a methylene bridge across the nine-membered ring, while the xenibellols possess a tricyclic core including a tetrahydrofuran ring. The absolute configuration and features of relative stereochemistry of many of these compounds are unknown; however, the absolute configuration for some isolates has been shown to vary depending upon the producing organism (e.g. soft corals/sea fans vs. symbiotic brown algae). There are at least twelve classes in the greater xenicane family consisting of over one hundred natural products; however, only four total syntheses (excluding xeniaphyllanes) have been reported to date. See Leumann et al., J. Org. Chem., 2000, 65, 9069; Corey et al., J. Am. Chem. Soc. 2008, 130, 2954; Altmann et al. Angew. Chem. Int. Ed. 2008, 47, 10081; and Williams et al., J. Am. Chem. Soc. 2009, 131, 9038.
Even though the xenicanes and related compounds, broadly defined, have been known in the literature for over thirty years, their scarcity and structural complexity have prevented the structure-activity relationship (SAR) studies necessary to enable complete medicinal valuation. Accordingly, there is currently a need for synthetic intermediates and methods that can be used to prepare xenicane compounds.